Antitumor effects of an NKT cell which have been known so far include (i) a direct effect on a tumor and (ii) an indirect effect on a tumor via maturation of a dendritic cell (adjuvant effect). As an immunotherapy using the NKT cell, an immunotherapy involving administration of a dendritic cell presenting a tumor antigen has been known, and studies for clinical application of such the immunotherapy have been conducted (Non-Patent Literatures 1 through 7). Further, an antigen-specific immunotherapy using a dendritic cell into which mRNA encoding a tumor antigen is introduced has been already established and clinically applied (Non-Patent Literatures 8 through 15). In order to introduce, into a cell material to be used, an antigen for immune induction in such immunotherapies, it is simple and easy to use an expression vector or the like. However, in a case where the expression vector is introduced into the cell in such an immunotherapy, that immunotherapy may be regarded as a gene therapy and application range thereof may be limited due to regulations. As a measure for avoiding this, introduction of RNA into a dendritic cell has been considered. However, this involves problems of a low introduction efficiency of RNA and a low expression level of a tumor antigen in the dendritic cell. In order to improve therapeutic effects of these immunotherapies, attempts to try various combinations with adjuvants have been made.
Another immunotherapy for a tumor is a peptide therapy involving use of a plurality of epitopes contained in a WT1 protein encoded by a Wilms tumor gene (Wilms tumor 1: WT1).
Meanwhile, the inventors of the subject application have developed unique immunotherapies (Patent Literatures 1, 2, etc.). Disclosed in Patent Literature 1 are (i) an abnormal cell which is isolated from a patient and has, on its surface, CD1d presenting an NKT cell ligand and (ii) a method for producing the cell (Patent Literature 1). This cell is capable of inducing both activation of NKT cells and tumor-specific immune response of T-cells. Disclosed in Patent Literature 2 are (i) an allo-cell which is not derived from a patient and has, on its surface, CD1d presenting an NKT cell ligand and in which a disease-specific antigen is expressed and (ii) a method for producing the cell. This allo-cell is capable of exhibiting immune inducibility similar to that of the cell disclosed in Patent Literature 1 without being isolated from a patient. Such the immunotherapies are expected to be applied to various antitumor immunotherapies for leukemia etc.